[CI] Add Decode Context Parallelism (DCP) test to CI

[minosfuture]

Purpose

Guard both hopper and blackwell support for DCP

Test Plan

local test CUDA_VISIBLE_DEVICES=0,1 pytest -v -s tests/distributed/test_context_parallel.py

Test Result

==================================================================================== warnings summary ====================================================================================
../../../../../home/yming/uv_env/vllm/lib64/python3.12/site-packages/schemathesis/generation/coverage.py:305
  /home/yming/uv_env/vllm/lib64/python3.12/site-packages/schemathesis/generation/coverage.py:305: DeprecationWarning: jsonschema.exceptions.RefResolutionError is deprecated as of version 4.18.0. If you wish to catch potential reference resolution errors, directly catch referencing.exceptions.Unresolvable.
    ref_error: type[Exception] = jsonschema.RefResolutionError,

tests/distributed/test_context_parallel.py::test_cp_generation[deepseek-ai/DeepSeek-V2-Lite-Chat-parallel_setup0-mp-1-auto-test_options0]
tests/distributed/test_context_parallel.py::test_cp_generation[deepseek-ai/DeepSeek-V2-Lite-Chat-parallel_setup1-mp-1-auto-test_options1]
tests/distributed/test_context_parallel.py::test_cp_generation[deepseek-ai/DeepSeek-V2-Lite-Chat-parallel_setup2-mp-1-auto-test_options2]
tests/distributed/test_context_parallel.py::test_cp_generation[deepseek-ai/DeepSeek-V2-Lite-Chat-parallel_setup3-mp-1-auto-test_options3]
  /data/users/yming/gitrepos/vllm/tests/utils.py:814: DeprecationWarning: This process (pid=1422877) is multi-threaded, use of fork() may lead to deadlocks in the child.
    pid = os.fork()

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
======================================================================= 4 passed, 5 warnings in 237.92s (0:03:57) ========================================================================

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request adds CI tests for Decode Context Parallelism (DCP) on Hopper and Blackwell architectures. The changes in the CI configuration and the test file are mostly correct and achieve this goal. I've found one potential issue in the test file that could make the test framework fragile for future changes and have suggested a fix.

[gemini-code-assist]

The list comprehension here assumes that the values in CP_TEXT_GENERATION_MODELS are always lists of CPTestSettings. This might be fragile if a new model is added with a single CPTestSettings object instead of a list. This would cause the test parameter generation to fail. To make this more robust, you could handle both cases by ensuring you're always iterating over a list.

Suggested change

	for setting in settings for params in setting.iter_params(model_id)
	for setting in (settings if isinstance(settings, list) else [settings]) for params in setting.iter_params(model_id)

[youkaichao]

merge into one hopper distributed tests ?

[minosfuture]

done

[simon-mo]

Can you check they actually run in CI by unblocking them?

[minosfuture]

unblocked added CI tests and they've passed. But the existing qwen moe test has been failing. I can reproduce that locally. I wonder if this qwen moe test is never executed as part of CI.
I'll debug this once I have some cycles. Tracking the issue here: #24797.
@youkaichao @simon-mo is it ok to merge this PR in?

[youkaichao]

sounds good, let's merge it first.